How do I troubleshoot a malfunctioning engine in my Audi A2?

My Audi A2's engine is not running smoothly and I'm not sure what the issue is. The check engine light is not on and the car still starts, but there is a noticeable lack of power. What steps can I take to diagnose and fix this problem?

First, check the spark plugs to see if they are dirty or worn out. If so, replace them with new ones. Next, check the air filter for any clogs or debris. A dirty air filter can cause the engine to run poorly. Make sure to replace it if needed. Also, check the fuel filter for any blockages. If it is dirty, replace it. These basic maintenance tasks can often solve engine performance issues.

Another potential cause could be a faulty oxygen sensor. This sensor measures the amount of oxygen in the exhaust and helps the car's computer regulate the fuel-air mixture. If the sensor is malfunctioning, it can cause the engine to run poorly. Have a mechanic check and replace the sensor if needed.